Autosomal Dominant Tubulointerstitial Kidney Disease: Clinical Presentation of Patients With ADTKD-UMOD and ADTKD-MUC1.

RATIONALE & OBJECTIVE: Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a rare underdiagnosed cause of end-stage renal disease (ESRD). ADTKD is caused by mutations in at least 4 different genes: MUC1, UMOD, HNF1B, and REN. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: 56 families (131 affected individuals) with ADTKD referred from different Spanish hospitals. Clinical, laboratory, radiologic, and pathologic data were collected, and genetic testing for UMOD, MUC1, REN, and HNF1B was performed. PREDICTORS: Hyperuricemia, ultrasound findings, renal histology, genetic mutations. OUTCOMES: Age at ESRD, rate of decline in estimated glomerular filtration rate. RESULTS: ADTKD was diagnosed in 25 families (45%), 9 carried UMOD pathogenic variants (41 affected members), and 16 carried the MUC1 pathogenic mutation c.(428)dupC (90 affected members). No pathogenic variants were identified in REN or HNF1B. Among the 77 individuals who developed ESRD, median age at onset of ESRD was 51 years for those with ADTKD-MUC1 versus 56 years (P=0.1) for those with ADTKD-UMOD. Individuals with the MUC1 duplication presented higher risk for developing ESRD (HR, 2.24; P=0.03). The slope of decline in estimated glomerular filtration rate showed no significant difference between groups (-3.0mL/min/1.73m2 per year in the ADTKD-UMOD group versus -3.9mL/min/1.73m2 per year in the ADTKD-MUC1 group; P=0.2). The prevalence of hyperuricemia was significantly higher in individuals with ADTKD-UMOD (87% vs 54%; P=0.006). Although gout occurred more frequently in this group, the difference was not statistically significant (24% vs 7%; P=0.07). LIMITATIONS: Relatively small Spanish cohort. MUC1 analysis limited to cytosine duplication. CONCLUSIONS: The main genetic cause of ADTKD in our Spanish cohort is the MUC1 pathogenic mutation c.(428)dupC. Renal survival may be worse in individuals with the MUC1 mutation than in those with UMOD mutations. Clinical presentation does not permit distinguishing between these variants. However, hyperuricemia and gout are more frequent in individuals with ADTKD-UMOD.